Does it work if you plug it out and plug it back in?
I haven't tried that.. but I do know that you need to compile cgminer with the proper libraries to enable usb hotplug and I don't think I did that.
No special libraries are required for hotplug.
You just need to be using devices that we've rewritten or converted over to my usbutils library.
If it mines on usbutils, it also has hotplug.
Currently that is: ModMinerQuad, BFL FPGA and BFL ASIC
ZTex is USB direct, but nelisky/dennisx wrote it before I wrote the new usbutils - so it doesn't have hotplug.
Switching over the Icarus driver will cover: Icarus, Lancelot, Cairnsmore1, AsicminerUSB
Ckolivas is converting over Avalon - though I'd not really think hotplug would be much in use there